In the little hole in the middle there's an IR receiver sensor for the remote control.
The projection screen on top of the cabinet. The screen is 84" x 84" matte white, great for projecting slides.
The horizontal arm extended a bit. Notice the Accuride 3640 slide that holds the whole mechanism.
The projection screen as seen from below.
Projection screen from below.
The projection screen at the top. The mechanism is securely attached to the cabinet by a piece of wood with three screws in it. Attached to it through the Accuride slide is the "drawer", which moves forward. Notice the two limit switches on the fixed piece of wood, used to signal when to stop the motor.
The box housing the microcontroller, and the rack and pinion, used to transform the rotational movement of the DC motor inside the box in linear movement.
Close up of the rack and the system that holds the screen.
The rack gear needs to perfectly match the rack, otherwise they won't work. The gear also need to securely attach to the motor spur, otherwise it will simply spin and not do anything.